atw 2018-02

inforum

atw Vol. 63 (2018) | Issue 2 ı February

RESEARCH AND INNOVATION 112

1.3 The innovation

The main features of this software and

study can be summarized as follows:

Exposure from all pathways is

included- Ingestion pathways are

modelled in such a detailed way

that, translocation, -transfer between

soil-plant, and feed-animal, food processing

and storage, weathering, and

dilution in the plant are all taken into

account. Time dependency in radionuclide

transfer in the environment

considering food harvesting, sowing

times, feeding regimes, and the

growing up of a person are all taken

into account. Individual doses for

maximum and average individuals

and for four age groups are calculated.

Doses in the case of implementation

of countermeasures are calculated.

Collective doses for big cities can be

calculated. Two different methods for

stochastic risk modelling are applied.

A probabilistic module has also

been developed; namely, uncertainty

analysis can be performed (if applicable).This

study is regarded as unique

since. The model algorithms, which

the KIANA Advance Computational

Computer Code developed for this

study was based on IAEA safety report

series [Müller, H. and Pröhl, G., 1993],

has been modified; the KIANA

Advance Computational Computer

Code to be able to calculate inhalation

doses from resuspension, individual

doses in terms of both average and

maximum habits, collective doses and

late risks, and to utilize the recent

knowledge in the dose and risk assessment

area to the extent possible, such

as dose conversion factors and risk

coefficients etc.

The long-range transport model,

which the code/software developed

for this study was coupled with,

was also upgraded to increase the

number of pollutants modelled to

provide us easiness. Besides, extensive

uncertainty and sensitivity analyses

associated with 96 parameters have

been performed for this study. The

meteorological module in the existing

environmental emergency response

system is associated with 3-day-

Domestic forecast meteorological

data acquired through the State

Meteorological Directorate. The dispersion

model is the Developed AIREM

and DOZAE M model that has the

capability to predict trajectories,

concentration, and deposition patterns

in the case of nuclear accidents and

normal operations. However, doses,

risks, and activities in the food chain

are not calculated with the existing

system in IRAN. Since the newly

developed KIANA Advance Computational

Computer Code for this

study is compatible with the existing

system's dispersion code, it can easily

be integrated into it.

2.1 Atmospheric dispersion

models

Numerous radiation dose calculation

tools have been developed over the

years. They calculate trajectories,

atmospheric transport and dispersion,

age-dependent radiation doses, early

and late health risks, monetary costs

of the accidents, doses in the case

of implementation of emergency

actions, collective health risk, uncertainty

analysis etc. Atmospheric

dispersion methods in these tools

can be based on simple Gaussian or

numerical approaches. Short-range

dispersion models usually use

straight-line Gaussian plume model.

These models are appropriate if the

release is from a source that has

dimensions, which are small compared

to the distances at which concentrations

are to be estimated. For

example, for the distances out to

5-10 km from the source point, if the

terrain is relatively flat and has

uniform surface conditions in all

directions and if the atmospheric

conditions at the time and location of

the release completely control the

transport and diffusion of material

in the atmosphere short-range

atmospheric dispersion models are

preferred. Gaussian dispersion equations

should be used to estimate concentrations

up to the 80 km from the

source under ideal conditions of flat

terrain and no spatial variations of the

wind field. Consequently, for a countrywide

dispersion simulation, due to

topo graphy and dispersion area, the

straight-line Gaussian models can not

be appropriate tools. Therefore, longrange

atmospheric dispersion models

are used in this paper. Dose assessment

methodology in some aforementioned

short range codes neglects

ingestion pathway and calculation

of doses in the late phase of the accident.

These are coupled with simple

radiation dose modelling algorithm,

including only inhalation and external

radiation pathways i.e. HotSpot,

RASCAL and RTARC [Homann, S. G.,

2010, Mcguire, S. A., Ramsdell, Jr., J. V.

and Athey, G. F., 2007, Stubna M. and

Kusovska Z. 1993] All radiation dose

exposure pathways can be seen in

Figure 1.

Since short range codes generally

calculate short-term doses incurred

immediately after the accident and

recommend emergency protective

actions, such as intervention, sheltering

and iodine pills, and long-term

effects incurred from the ingestion

pathway are not generally calculated

with these types of codes. Some of

the codes having a Gaussian plume

methodology calculates ingestion

doses, but not in a dynamic or

| | Fig. 1.

Radiation Dose Exposure Pathways in KIANA Advance Computational Computer Code.

Research and Innovation

Design and Development of a Radio eco logical Domestic User Friendly Code for Calculation of Radiation Doses and Concentration due to Airborn Radio nuclides Release

A. Haghighi Shad, D. Masti, M. Athari Allaf, K. Sepanloo, S.A.H. Feghhi and R. Khodadadi

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